Partial Plate Solving Fail During Time Series - Images Look the Same to Me

Partial Plate Solving Fail During Time Series - Images Look the Same to Me

Hello! I've been imaging DL HER with a time series. Several times, in the middleend of the run, the images cannot be Plate Solved. They look exactly the same to me as the ones that can be plate solved.

I'd like to find out why they weren't Plate Solved so that I can make appropriate adjustments. I woud appreciate gjuidance as to how to do this.

I've attached JPEG of the final image in the run that was Plate Solved (V-24) and the first one of the group in the series that was not (V-25). Interestingly, V-24 is actually a worse image than V-25 even though it was plate solved

I'm happy to share the images of the complete run in VPHOT with anyone who might like to check them out. They are calibrated even though VPHOT says not. Best regards.

Note that once in a while, for a not visually obvious reason, pin-point will fail. The first thing for you to do is confirm that the image scale of your image matches with the image scale listed in your telescope setup under admin. Did you take binning into account? I suspect you have entered this value before. If not, VPhot/Pinpoint is assuming a value of 2"/pix.

I suspect this does not happen often? If so, it may just be one of those rare, uncertain pin-point failures with no easy explanation? ;-(

In the boxes at the far left, click in the box for one of stars that did plate sollve, then click in the boxes for all the stars that didn't plate solve. From the menu click on WCS, then refresh. I have used this only a few times, but it usually works. If Ken has a different way to do this I would certainly defer to him.

Hello! I tried Phil's technique again. I thought it had worked, but it ended up not plate solving the images.

Doing it, all images turned green with WCS. However, when I went to analyze them, VPHOT still did not identify them or plate solve them.

I ran DL HER again last night and the same thing happened. I deleted the previous run and uploaded the current images that are problematic.

Of note, I use MPO CANOPUS for reductions and to create an AAVSO submission report. The images I uploaded to VPHOT are the ones that CANOPUS did not match. VPHOT matches about 1/3 to 1/2 of them.

The camera is rotated about 170 degrees, but this is noted in the FITS header.

I am not sure why DL HER is having a problem. Half way through the time series, the images plate solve. Then, about half way through, the images do not plate solve even though visually they look exactly the same. Best regards.

The images you shared with me do act a little strangely? They do show RA/Dec after I did a WCS update? When I clicked AAVSO comps, it said not right filter even though it was a V filter in header?

BTW, what do you mean by "Canopus did not match"? Did you rotate at meridian flip or are all your images rotated that amount. IOW, you have not tried to square up the camera? It should not have to be at 0. I have one camera set at 270. Does this happen with any other targets? Something new? I did notice that your FOV shifts continuously during the run. Need a better polar alignment?

My fault with this. An unusual error, though, which I could not figure out till Brian Warner provided guidance and helped me with with the Canopus program plate solving..

I had reversed the declination minutes for DL HER in the script - 23 arc-minutes instead of 32 arc-minutes.

Something unusual was still going on since the images from the first half of the DL HER time series actually had the correct declination of 32 arc-minutes in the FITS header that matched the actual image center of 32 arc-minutes even though the script had called for a declination of 23 arc-minutes. (Probably coming from the previous ASAS target that had a nearly identical declination and was only 6 arc-minutes away from DL HER.)

Something happened about half way through the DL HER time series when the script put 23 arc-minutes into the FITS header but failed to slew the scope to the new coordinates. As a result, the stated image center and actual image center differed and the resultant images could not be plate solved.

Hello! I just ran DL HER again last night making sure the correct coordinates (32' rather than 23' in DEC). Again, halfway through the 3-hour run, the FITs header reversed the Dec minute digits - to 23' instead of 32'(the actual image was unchanged) so Canopus could not plate solve it. Interestingly, the FITS header again reversed the Dec back to 32' from 23' towards the end of the run (again, with the actual image unchanged.)

Anyway, not a VPHOT issue. I'm going to work with SGPro on this and see where the glitch is - probably in how I've set up something in the run. Best regards.